Bill's first job was at Salem University Hospital, where his father worked. It was during this time that he met Dr. Laura Spencer, a young psychiatric intern, and began dating her. His brother Mickey was also interested in Dr. Spencer. Although this caused problems with Mickey, Laura and Bill soon became engaged, in 1966. Bill was stricken with bone tuberculosis and it appeared as though he would never be able to become a surgeon. Bill was devastated and left Salem, in 1966, to sort out his future and eventually took a medical position in another town.

In late 1967 Bill returned to Salem along with his friend Dr. Mark Brooks and a little boy name Timmy McCall. Bill had been living with the McCall family when Timmy's mother Mary died, but before passing made Bill promise to become Timmy's guardian. He met Mark Brooks through Mary, and it was Mark who encouraged Bill to undergo therapy to regain control of his hand. When Timmy McCall needed his appendix removed Bill performed the surgery, and knew he would be able to return to Salem and continue his surgical career.

While Bill had been out of town, his brother Mickey, and his ex-fiance became closer and thy soon became engaged. After Mickey and Laura had wed Bill was consumed with jealousy, and one night, while drunk, Bill raped Laura in her office. When he awoke the next morning Bill could not remember anything that had happened. Laura told him she turned him away, in order to prevent a feud between Mickey, her husband, and Bill.[2]

Laura soon became pregnant. Tom found out about the pregnancy from a lab report and also found that Mickey was sterile. Laura explained to Tom that Bill had raped her while he was drunk and that she didn't tell Mickey in order to prevent any fighting between the two. Tom agreed to keep the secret. Bill had also read the report about Mickey's infertility, but kept it to himself because he felt it was best that no one know. Laura soon delivered the baby, Michael William Horton, on September 28, 1968.

Everyone's happiness would soon be ruined when Bill learned that Kitty Horton, Tommy's ex-wife, had a tape recording of Laura and Tom Horton talking about Michael in which they revealed he was Michael's natural father. Bill went to Kitty's apartment and refused to play games. Bill ransacked her apartment and fought with Kitty before finding the tape and leaving. That wasn't the last of the trouble Kitty would cause for the Horton family. Kitty was killed later that night; Bill was eventually charged with Kitty's murder and Mickey defended Bill in court. Bill refused to tell anyone why he was at Kitty's place that night, and eventually he would be found guilty of involuntary manslaughter and be sentenced to 3 years in prison.

In prison Bill would meet Doug Williams, and his stories of Salem and a rich widowed Susan Martin would send Doug to Salem after he was released. Near the end of 1970 Bill was released from prison and later began seeing his brothers secretary Linda Patterson.

In 1972 Bill and Laura began to fall in love when Laura learned the true reason Bill went to jail. Laura planned to divorce Mickey and marry Bill. When the two were overheard talking by Mike, Mike assumed they were having an affair and ran out into the street and was hit by a car. Mike would survive, but afterwards he told his uncle Bill he hated him and to stay away from his family.

In 1973 Mickey would suffer a massive coronary, but with Bill's skilled hands he managed to save his brothers life. Soon after his operation Mickey would suddenly disappear from Salem. With Mickey out of the way Bill was free to pursue Laura, but her marriage to Mickey still stood in the way. When Mickey was discovered to be alive he granted Laura a divorce so he could remain with Maggie Simmons.

On December 4, 1975, after years of pursuing one another, Bill and Laura Horton were married, and a year later Laura gave birth to their daughter Jennifer Rose Horton on February 6, 1976. In 1976 the truth about Mike's parentage came out when Mike was injured while repairing a truck on Maggie Simmons' farm. Mickey and Laura both donated blood to save Mike's life, but neither matched. Mickey found out through Bill's medical records that Bill was a match, and Mickey's memory quickly flooded back. Mickey was enraged and bought a gun and went after Bill. Mickey waited for Bill to come home, and when he did they both fought over the gun. Bill ended up being shot in the arm, and Mickey suffered a mental breakdown. Mickey would be admitted to Belview Sanitarium for one year following the incident.

After the birth of his daughter Jennifer, Bill's wife Laura fell into a deep depression, but overcame it with Bill and Dr. Marlena Evans help. In 1978, Bill began having an affair with coworker Dr. Kate Winograd. He eventually left Laura to live with Kate, but when he realized he still loved Laura he returned to her and tried to repair their relationship. Kate had a child by Bill, Lucas Roberts.

In 1980, after putting his wife Laura into a sanitarium, Bill left Salem and left his daughter Jennifer with Tom and Alice Horton.

Bill returned in 1987 and began dating Janice Barnes. He eventually broke things off when his guilt about Laura grew too strong. Bill focused his attention on Jen and tried to put an end to his daughter's relationship with Frankie Brady. Jen retaliated by becoming engaged to Frankie, but broke it off when she feared she may become schizophrenic like her mother and grandmother.

Bill returned briefly in 1994 when Laura came home from the sanitarium. Bill also wanted to meet his son Lucas, but was coldly greeted by the young man. Bill left and went to Africa and later, Jennifer, Jack, and Abigail would join him there. Bill and ex-wife Laura returned to Salem in June 2010 when they received news that Alice Horton was extremely ill.